ECM digital microphone temperature compensation

Abstract

This document discusses, among other things, systems and methods to at least partially compensate for temperature sensitivity in a digital microphone system including, for example, a temperature sensitive membrane, such as an electrets condenser microphone (ECM).

What is claimed is: 
     
       1. A system, comprising:
 a temperature compensation circuit for a digital microphone system, the temperature compensation circuit including:
 a temperature dependent component configured to provide a first reference with respect to a temperature independent voltage reference; and 
 a voltage divider configured to provide second and third references with respect to the temperature independent voltage reference, 
 
 wherein the temperature compensation circuit is configured to provide a voltage reference configured to at least partially compensate for a temperature sensitivity of a digital microphone system using the third reference and a difference between the first and second references. 
 
     
     
       2. The system of  claim 1 , including:
 the temperature independent voltage reference, 
 wherein the temperature independent voltage reference includes a bandgap voltage reference, and 
 wherein the bandgap voltage reference includes a diode. 
 
     
     
       3. The system of  claim 2 , wherein the temperature dependent component includes a diode, and wherein the diode of the temperature dependent component matches the diode of the bandgap voltage reference. 
     
     
       4. The system of  claim 1 , wherein the temperature dependent component includes a diode. 
     
     
       5. The system of  claim 1 , wherein the digital microphone system includes a temperature sensitive membrane. 
     
     
       6. The system of  claim 5 , wherein the digital microphone system includes an electret condenser microphone (ECM), the ECM including the temperature sensitive membrane. 
     
     
       7. The system of  claim 6 , including:
 the ECM. 
 
     
     
       8. The system of  claim 1 , wherein the digital microphone system includes an electret membrane having a temperature sensitivity, and wherein the temperature compensation circuit is configured to at least partially compensate for the temperature sensitivity of the electret membrane. 
     
     
       9. The system of  claim 1 , including:
 the digital microphone system, the digital microphone system including:
 a microphone including a temperature sensitive membrane; 
 a pre-amplifier configured to receive information from the microphone; and 
 an analog-to-digital converter (ADC) configured to receive information from the pre-amplifier and to receive the reference voltage from the temperature compensation circuit. 
 
 
     
     
       10. The system of  claim 1 , wherein the voltage divider includes a resistor divider network including first, second, and third resistors coupled in series, wherein the first, second, and third resistors have a common temperature coefficient. 
     
     
       11. The system of  claim 1 , including:
 an amplifier configured to receive the first, second, and third references and to provide the voltage reference using a sum of:
 (1) the third reference, and 
 (2) a difference between the first and second references. 
 
 
     
     
       12. A method, comprising:
 providing a first reference, using a temperature dependent component, with respect to a temperature independent voltage reference; 
 providing second and third references, using a voltage divider, with respect to the temperature independent voltage reference; 
 providing a voltage reference using a temperature compensation circuit as a function of the third reference and a difference between the first and second references; and 
 at least partially compensating for a temperature sensitivity of a digital microphone system using the voltage reference. 
 
     
     
       13. The method of  claim 12 , including:
 providing the temperature independent voltage reference using a bandgap voltage reference, the bandgap voltage reference including a diode. 
 
     
     
       14. The method of  claim 13 , wherein the temperature dependent component includes a diode, and wherein the diode of the temperature dependent component matches the diode of the bandgap voltage reference. 
     
     
       15. The method of  claim 12 , wherein the temperature dependent component includes a diode. 
     
     
       16. The method of  claim 12 , wherein the digital microphone system includes a temperature sensitive membrane. 
     
     
       17. The method of  claim 16 , wherein the digital microphone system includes an electret condenser microphone (ECM), the ECM including the temperature sensitive membrane. 
     
     
       18. The method of  claim 12 , wherein the digital microphone system includes an electret membrane having a temperature sensitivity, and wherein the at least partially compensating for the temperature sensitivity includes at least partially compensating for the temperature sensitivity of the electret membrane. 
     
     
       19. The method of  claim 12 , wherein the voltage divider includes a resistor divider network including first, second, and third resistors coupled in series, wherein the first, second, and third resistors have a common temperature coefficient. 
     
     
       20. The method of  claim 12 , wherein the providing the voltage reference includes receiving the first, second, and third references using an amplifier and providing the voltage reference using a sum of:
 (1) the third reference, and 
 (2) a difference between the first and second references. 
 
     
     
       21. A system, comprising:
 a bandgap voltage reference including a diode; and 
 a temperature compensation circuit for a digital microphone system including an electret condenser microphone (ECM), the temperature compensation circuit including:
 a diode configured to provide a first reference with respect to the bandgap voltage reference; and 
 a resistor divider network including first, second, and third resistors coupled in series, the resistor divider network configured to provide second and third references with respect to the bandgap voltage reference; 
 
 wherein the temperature compensation circuit is configured to provide a voltage reference configured to at least partially compensate for a temperature sensitivity of a digital microphone system using a sum of:
 (1) the third reference, and 
 (2) a difference between the first and second references, and 
 
 wherein the diode of the bandgap voltage reference matches the diode of the temperature compensation circuit.